Timers, electronic

The main timer types are precision reference, electronic, mechanical, pyrotechnic, flueric and electrochemical. Also covered are fluid timers (not to be confused with flueric timers) and nuclear decay timers. Electronic and flueric timers are similar in that they both use oscillators, amplifiers, and related networks to achieve tuning and frequency control. In mechanical... 

These may be used to feed the solenoid or the motor of an interrupting device (such as an electrically operated breaker), indicating lights and circuits, auxiliary contactors or relays, electrical or electronic timers, hooters or buzzers, and all such auxiliary components and devices mounted on a controlgear or a switchgear assembly requiring a specified control voltage. 

Electronic Flow Calibrators These units are high accuracy electronic bubble flowmeters that provide instantaneous air flow readings and a cumulative averaging of multiple samples. These calibrators measure the flow rate of gases and report volume per unit of time. The timer is capable of detecting a soap film at 80... 

To meet the 1993 Energy Standards, the industry undertook, at considerable cost, the optimization of the various refrigeration system components. The most significant improvement was the increase in compressor efficiency, from an EER of about 4 to about 5.5. Other system improvements included more efficient fan motors, more effective heat transfer by the evaporator and the condenser, and less defrost energy. In the early 1980s, both the Whirlpool Corporation and White Consolidate Industries introduced electronic defrost controls. Heretofore, an electric timer initiated the defrost cycle, typically every t A elve hours, whether the evaporator needed it or not. With the electronic control the defrost inteiwal is more a function of frost accumulation than of time, and thus referred to as a variable defrost control or as adaptive defrost. It saves energy by being activated only when needed. 

The concentration of 222Rn in air was determined with a radon measurement detector. The detector allows realizing continuous radon monitoring. It consists of an electronic unit and a scintillation cell. The electronic unit contains power supply, amplifier, discriminator, timer, counter, and indicator. The scintillation cell contains the zinc sulfide scintillator, photomultiplier, preamplifier, high voltage power supply and chamber with a volume of 200 mL over the scintillator. This chamber is filled with the gas to be analyzed. The air is either pumped or diffuses into the scintillation cell. The scintillation count is processed by electronics, and radon concentrations for predetermined intervals are stored in the memory of the device. 

The three major types of electronic controllers are timers, electromechanical relays, and programmable logic controllers (PLCs), which are often called digital relays. Each of these types of controller is discussed in more detail below. 

In contrast to timers, which have internal triggers based on a regular schedule, electromechanical relays and PLCs have both external inputs and external outputs. However, PLCs are more flexible and more powerful than are electromechanical relays, and thus this section focuses primarily on PLCs as the predominant technology for security-related electronic control applications. 

Standard domestic microwave oven rated at 700-1000 W, with turntable for constant temperature and electronic digital timer control. 

A schematic diagram of the automatic system is shown in Fig. 4.12. It consists of five component modules a sample introduction unit, a digestion unit, a neutrafization vessel, a chelation and extraction vessel and an extract collection unit. The sy stem is controlled by a series of interacting cam and electronic process timers. 

In a typical electronic fuze timer the fundamental components are an oscillator and a binary counter. Lining flueric tech-... 

Viscosity measurements were made with two Cannon-Ubbelohde viscometers, and timing was by an optical device actuating an electronic timer (Wescan Instruments, Inc.). An air thermostat was used. The viscometers were calibrated with redistilled air-saturated water over the range 10°-50°C. The kinetic-energy correction was used in the form ... 

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